Packages you will need:
library(RColorBrewer)
library(leaflet)
library(ggplot2)
library(mapview)
library(raster)
library(htmltools)
library(leaflet.extras)## Warning: package 'leaflet.extras' was built under R version 3.5.3You can get admin level 2 boundaries for Nepal from GADM (using raster package),
If you don’t have internet, you can read in shapefiles from your drive
Then generate some dummy data:
Nepal2 <- getData('GADM', country='NPL', level=2)
Nepal2$cases <- sample(0:100, nrow(Nepal2), replace=T)
# create a new field to show (made-up) rate
Nepal2$population <- sample(10000:30000, nrow(Nepal2), replace=T)
Nepal2$rate <- round(Nepal2$cases/Nepal2$population*10000,1)Define color gradients- you can choose as many colours as you like e.g. red-yellow-green
Then produce a palette mapping the values in our dataframe to this gradient
Or you can map the data to one of R’s pre-defined palettes (e.g. “Blues”)
Total_gradient <- c("white", "brown1" )
palTotal <- colorBin(Total_gradient, domain = Nepal2$cases, bins = quantile(Nepal2$cases))
palRate <- colorBin("Blues", domain = Nepal2$rate, bins = quantile(Nepal2$rate))Use leaflet to display a blank map with OpenStreetMap imagery
map <-leaflet() %>%
addProviderTiles(providers$OpenStreetMap)
mapThis generates a simple, non-interactive map Here we just define the outline and fill style, and assign the layer to a group There are numerous other options for you to explore Try making the lines dashed instead
Map_Nepal <- map %>% ## use the pipe operator to add elements
## to the OpenStreet base map
addPolygons(data=Nepal2, ## Use data from the spatial polygons dataframe Nepal2
color = 'black', ## line color
weight =2, ## line width
opacity = 1, ## line opacity
fillColor= ~palTotal(cases), ## fill polygons using the palette we generated
fillOpacity = 1, ## opaque fill
group = "Number of cases") ## allows this element to be linked e.g. to legend
Map_NepalWhen we start adding more layers to the map, we will need a control panel so the user can choose which layers to display
We will also need a layers panel that should be linked to the data and the control panel
Map_Nepal <- Map_Nepal %>% ## again we use the pipe operator
## to add complexity to our existing map object
## E.g. add the "Number of cases" group to the layers panel.
addLayersControl(overlayGroups = c("Number of cases")) %>%
## Currently this group only contains the polygons showing number of cases.
## Add a Legend
addLegend(pal = palTotal, ## use same palette as for polygons
values = Nepal2$cases, ## use same values
opacity = 1, ## self-explanatory
title = "Number of cases", ## "
position = "bottomleft", ## "
group = "Number of cases", ## links this legend with the polygons
labFormat = labelFormat(digits = 0)) ## define decimal places
Map_NepalWe can add layers showing other fields just by changing the fillColor argument and assigning it to a new group
To make your map consistent, its usually best to keep the other options (e.g. line style) the same
Map_Nepal <- Map_Nepal %>%
addPolygons(data=Nepal2,
weight=2,
opacity= 1,
color= 'black',
fillColor= ~palRate(rate), ## colour by rate
fillOpacity= 1,
group = "Rate") %>% ## new group
# Layers control
addLayersControl(overlayGroups = c("Number of cases", "Rate"), ## as before but with 2 groups
options = layersControlOptions(collapsed = FALSE))%>% ## this keeps the panel expanded
# Legend
addLegend(pal = palRate,
values = Nepal2$rate,
opacity = 1,
title = "Rate (per 10,000)",
position = "bottomleft",
group = "Rate",
labFormat = labelFormat(digits = 1))
Map_NepalThis is a long chunk of code but it is just putting together what we have done above, and adding highlight and label options.
You could also look at this Example from leaflet
## define labels using the sprintf() function to format text
number_labels <- sprintf(
"<strong>%s</strong><br/>%d cases", # this is C-style formatting which means
Nepal2$NAME_2, Nepal2$cases # "print NAME_2 in bold font, return,
# print the number of cases in normal font"
) %>% lapply(htmltools::HTML)
rate_labels <- sprintf(
"<strong>%s</strong><br/>%g cases per 10,000",
Nepal2$NAME_2, round(Nepal2$rate, digits = 1)
) %>% lapply(htmltools::HTML)
## Add these labels to the map, along with highlighting options
## Number layer - inital options as above
Map_Nepal <- map %>%
addPolygons(data=Nepal2,
fillColor= ~palTotal(cases),
fillOpacity = 1,
color = 'black',
weight =2,
opacity = 1,
group = "Number of cases",
highlight = highlightOptions( # When user hovers, give the polygon:
weight = 4, # A thicker outline
color = "#666"), # A grey outline
label = number_labels, # The label we defined as number_labels
labelOptions = labelOptions(
textsize = "15px")) %>%
## rate
addPolygons(data=Nepal2,
fillColor= ~palRate(rate),
fillOpacity= 1,
color= 'black',
weight=2,
opacity= 1,
group = "Rate",
highlight = highlightOptions(
weight = 4,
color = "#666"),
label = rate_labels,
labelOptions = labelOptions(
textsize = "15px")) %>%
# Layers control
addLayersControl(overlayGroups = c("Number of cases", "Rate"),
options = layersControlOptions(collapsed = FALSE))%>%
# Legend
addLegend(pal = palTotal,
values = Nepal2$cases,
opacity = 1,
title = "Number of cases",
position = "bottomleft",
group = "Number of cases",
labFormat = labelFormat(digits = 0))%>%
addLegend(pal = palRate,
values = Nepal2$rate,
opacity = 0.7,
title = "Rate (per 10,000)",
position = "bottomleft",
group = "Rate",
labFormat = labelFormat(digits = 1))%>%
hideGroup("Rate") ## This means only the first group will be displayed initially
Map_NepalIf you are making the map for a funder, a programme or any other external partner, you may need to add their logo
The url option is really useful if your maps are going to appear on a separate webpage
Map_Nepal <- Map_Nepal%>% addLogo(img =
"http://blogs.lshtm.ac.uk/inthenews/files/2017/12/LSHTM-logo-bw-1.jpg",
url = "https://www.lshtm.ac.uk/",
position = "topleft",
width = 120,
height = 60) %>% addMeasure()
Map_Nepal